Forscher versuchen, mit der Stringtheorie die Teilchenwelt zu
Werbung
128 Mathematik, aber noch nicht, was »We understand the mathematics, but not what it is trying to tell us« Forscher versuchen, mit der Stringtheorie die Teilchenwelt zu ergründen researchers are using the string theory to explore the world of particles Mit den Physikern Jan Plefka und Matthias Staudacher sprach Sabine Sütterlin an interview with the physicians Jan Plefka and Matthias staudacher by sabine sütterlin http://u.hu-berlin.de/plefka http://u.hu-berlin.de/staudacher tEilCHENPHysiK / PartiClE PHysiCs 129 k deutsch Die mathematischen Physiker Matthias Staudacher und Jan Plefka erforschen, ob sich die Gravitation mithilfe der Stringtheorie in satz: Mit dem richtigen mathematischen Modell lässt sich die Gravitation gleichzeitig mit beiden Theorien beschreiben. Strings sind schwingende Energiefädchen, die das Teilchenkonzept ersetzen Kann ein Laie verstehen, was Stringtheorie ist? Plefka: strings are vibrating energy strings that replace the particle concept - - Das wären Teilchen, die Gravitation vermitteln, also das, was Warum strebt man diese Vereinheitlichung an? Plefka: Plefka: - Staudacher: - - - - Was genau erforschen Sie an der Stringtheorie? Staudacher: - - Aus dem Teilchenzoo From the world of particles kleinere Grundbausteine unserer Materie entdeckt. Welche Teilchen aber das endgültige Ende darstellen, wissen sie noch nicht. over the years scientists have discovered smaller and smaller building blocks of matter. However, as yet, they still do not know which parti- Atome / Atoms Sie bestehen aus Neutronen, Protonen und Elektronen und sind nicht die kleinsten Teilchen der Materie, wie man einst glaubte. atoms consist of neutrons, protons and electrons, but are not the smallest particle of matter as was once presumed. Gluonen / Gluons Elementarteilchen, die indirekt für die Anziehung von Protonen und Neutronen in einem Atomkern verantwortlich sind. Gluons are elementary particles which are indirectly responsible for the attraction of protons and neutrons in an atom nucleus. Hadronen / Hadrons sind seit der Entdeckung der Quarks keine Elementarteilchen mehr, sie sind aus Quarks oder deren Antiteilchen zusammengesetzt, die bekanntesten Hadronen sind Nukleonen (Neutronen und Protonen) aus denen die Atomkerne aufgebaut sind. since the discovery of quarks, hadrons are no longer seen as elementary particles, as they are composed of quarks or their antiparticles. the best known hadrons are nucleons (neutrons and protons) which form the nucleus of atoms. Large Hadron Collider Kernforschungszentrum Cern bei Genf. Hier prallen Teilchen mit hoher Energie aufeinander, Physiker interessieren die dabei entstehenden neuen Teilchen. the lHC is a particle accelerator housed at the European Centre for Nuclear research CErN in Geneva. the instrument enables scientists to smash particles together at extremely high speeds. Physicists are particularly interested in the resulting new particles. - Quarks Elementarteilchen, die Bestandteile von Protoquarks Quarks are the principle components of proquarks: six regular quarks and six anti-quarks. Strings genaugenommen sind sie gar keine Teilchen, Teilchenkonzept ersetzen. Ihre Existenz ist im Gegensatz zu den oben genannten Elementarteilchen aber noch nicht erwiesen. to be precise, strings are not particles but vibrating energy strings that replace the particle concept. However, in contrast to the aforementioned elementary particles, their existence has Staudacher: - Wie kann man sich mehr als drei Raumdimensionen vorstellen? Plefka: - - Plefka: - tEilCHENPHysiK / PartiClE PHysiCs 131 Staudacher: - Sie sprachen aber von sechs zusätzlichen Dimensionen. Wie geht das? Staudacher: - Was genau tun Sie, wenn Sie forschen? Staudacher: - 132 Jan Plefka hat an der Technischen Universiver promoviert. Habilitiert wurde er am Insti2006 bis 2010 hatte er eine Lichtenberg-Pro- dert werden. Seit Februar 2011 ist er Professor für »Quantenfeldtheorie jenseits des Standardmodells und Stringtheorie«. Plefka ist Sprecher des DFG-Graduiertenkollegs »Masse, Spektrum, Symmetrie« und leitet Projekte im DFG-Sonderforschungsbereich »Raum-Zeit-Materie«. Jan Plefka studied physics at the technische Universität darmstadt and the texas a&M University, and received his doctorate from the University of Hanover. He was promoted to professor at the department of Physics of the Humboldt-Universität. Between 2006 and 2010, he held a lichtenberg Professorship of the Volkswagen Foundation, which promotes aspiring young researchers involved in innovative projects. He has been professor for »Quantum Field theory beyond the standard Model and string theory« since February 2011. Plefka is the spokesperson of the dFG research training Group »Mass, spectrum, symmetry« and manages projects in the dFG sFB research venture »space-time-Matter«. k english The mathematical physicists Matthias Staudacher and Jan Plefka with the right mathematical model it is possible to describe gravity simultaneously with both theories. Matthias Staudacher ist seit 2010 Professor für Mathematische Physik von Raum, Zeit und Materie an den Instituten für Physik und ten Heidelberg und München (LMU) sowie an der University of Illinois in Urbana-Champaign, wo er 1990 über Matrixmodelle der zweidimensionalen Quantengravitation promovierte. Von 1997 bis 2010 arbeitete er als Forschungsgruppenleiter in der Abteilung Quantengravitation und Vereinheitlichte Theorien am Potsdamer Max-Planck-Institut für Gravitationsphysik. Für seine herausra- Can a layperson really understand the String Theory? Plefka: The concept is quite easy to explain. Ordinarily, elementary particles are pictured as a point. In other words, neither the fundamental particles, upon which the structure of matter is based, nor the force particles, which are responsible for mediating interactions, vibrate. The fundamental premise of the String Theory, however, states exactly the opposite: that they display the vibrations of a string-like object. The idea has exciting implications: it is obvious that in addition to the four known dimensions of space and time there must be an additional six, otherwise the String Theory would not be mathematically consistent. Furthermore, the strings also describe the gravitons, which are very special force particles. Matthias Staudacher has been Professor for Mathematical Physics of space, time and Matter at the department of Physics and the department of Mathematics of the Humboldt-Universität zu Berlin since 2010. He studied physics at Heidelberg University, at lMU Munich and at the University of illinois at Urbana-Champaign, where, in 1990, he received his doctorate for his thesis on Matrix Models of two-dimensional Quantum Gravity. Between 1997 and 2010, he worked as a research group leader at the department of er 2009 mit dem Akademiepreis der BerlinBrandenburgischen Akademie der Wissen- Max Planck institute for Gravitational Physics in Potsdam. in 2009, he was awarded the academy award of the Berlin-Brandenburg academy of sciences and Humanities for his Seine Forschungsschwerpunkte sind: Quantenfeldtheorie, yang-Mills Theorien, rable Modelle, Matrixmodelle His main areas of research include: Quantum Field theory, yang-Mills theories, string theory, Gauge/string duality, integrable Models, Matrix Models. Are these the particles which mediate gravitational interaction, generally referred to as gravity? Plefka: We do not know whether they are ordinary particles. But it is to do with gravity: as a consequence of the Standard Model tum Field Theory can describe three natural physical forces, the well-known electromagnetic force, as well as the strong and weak nuclear force, which are only important at subatomic level. However, it has not yet been possible to describe gravitation with tEilCHENPHysiK / PartiClE PHysiCs 133 »Wir haben eine Methode entwickelt, mit der sich zeigen lässt, dass es sich bei beiden Standpunkten – Strings und Teilchen – um exakt dasselbe Phänomen handelt« »We have developed a method which allows us to show that both positions – strings and particles – are exactly the same phenomena« staudacher: diction of Einstein’s Theory of Relativity, which functions wonderfully on cosmic scales. But on short length scales there are phecreation of matter during the Big Bang or in the vicinity of black natural forces. What exactly does your String Theory research entail? staudacher: surprising interpretation of the String Theory, on the so-called AdS/CFT principle. It involves dual description of the same physical phenomena; in other words, with which, on top of everything, are actually 1997. For a long time it was unclear whether it was just approximate or precise. We have developed a method which allows us to show that both positions – strings and particles – are exactly the same phenomena. We initially took an idealised ten dimensional system that does not actually occur in nature, but which is fairly close to reality and boasts this duality. The system is precisely soluble. This proves that it can be described with both the String Theory prototype in a bid to get closer to reality. Plefka: ory, we can, for example, predict which scattering processes occur when two particles are smashed together at high speeds during an experiment in a particle accelerator. However, this is only possible when the coupling force between the two particles is low. If we consider the question of why a proton, consisting of quarks and gluons, is stable – in other words, why matter assumes such a bound state -, we are unable to answer it with the mathematical these particles are too great. 134 Plefka: What we are doing is basically an in-depth exploration of what Maldacena proposed. Mathematically speaking we can say it is possible, but we would now also like to illustrate why it is possible, meaning how the particles become strings and vice versa. staudacher: We understand the mathematics, but not what it is be calculated in both descriptions. It is becoming increasingly possible to achieve this exactly on both sides. How is it possible to imagine more than three spatial dimensions? Plefka: We view a world that has one time and three spatial dimensions. Let us imagine two elementary particles, for example quarks, which are connected by a strong force. In our theory, this force is mediated via a string which hangs in a higher dimension. If I pull the particles apart, it feels like an elastic band that is being stretched into a higher dimension. In this case, duality means that every elementary particle in our world represents the end position of a string. »Die Stringtheorie führt zusammen« gravitational force and the other natural forces« staudacher: Maybe you can imagine the additional dimensions as a type of shadow play. We see the shadows on the screen, but not the hands and the light source that project the image onto the screen. We have to use mathematical methods to open up this invisible world. You mentioned six additional dimensions. How is that possible? staudacher: which the String Theory occurs. You can also adopt the point of view that strings are one dimensional structures which move in time, thus spanning an area. That is to say, you can also describe our world in this picture as being two dimensional. We can therefore describe the same physical object in a two, four and ten dimensional language. This game of dimensions really enthrals researchers. What do you do exactly when you are researching? staudacher: (laughs and gestures to the board full of formulas domain with primarily analytical goals. Most of the work takes place with a pencil and paper or on the good old board. It is important to discuss issues with others in order to get new ideas. possible. v tEilCHENPHysiK / PartiClE PHysiCs 135